cs-413 1 time management (part 9) bilgisayar mühendisliği bölümü – bilkent Üniversitesi –...

1CS-413

Time Management (Part 9)

Bilgisayar Mühendisliği Bölümü – Bilkent Üniversitesi – Fall 2009

Dr.Çağatay ÜNDEĞER

InstructorBilkent University, Computer Engineering

Middle East Technical University, Game Technologies

&

General ManagerSimBT Inc.

e-mail : [email protected]

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Time Management

• Project Management Components (knowledge areas)– Project Integration Management– Project Scope Management– Project Time Management– Project Cost Management– Project Human Resource Management– Project Communication Management– Project Quality Management– Project Risk Management– Project Procurement Management

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Time Management

• Introduction• Activity Definition• Activity Sequencing• Activity Duration Estimation• Schedule Development• Schedule Control

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Time Management(Introduction)

• Includes the process required to ensure timely completion of project.

• Follows a “divide and conquer” strategy of breaking down a project into components that can be managed and controlled more easily.

• Once components are determined, – A sequence for doing the work tasks

(schedule) is established, – Resources are assigned to those tasks, – Durations of tasks are estimated.

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• A project schedule generally created early in the project,– During initiation and planning.

• However,– Schedules are used in execution phases to

help development; and– They will force development team to met

some timing constraints (milestones).

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• Schedules (except some milestones) may frequently need to be updated as the project progress.

• As project moves forward, – Estimations become more accurate.

• This is reffered as cone of uncertainty [Barry Boehm 1981].

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• Cone of uncertainty:– A progressively more detailed and

accurate projection of project schedule and duration as project deliverables and activities are specified in more detail.

Feasibility ConceptOperation

RequirementsSpecification

ProductDesign

DetailSpecification

AcceptedSoftware

1

0.1

10

2

0.5

Cone of uncertainty from Boehm

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• According to PMI;– At very early phases:

• Magnitude estimates: +75% -25%.– After components are specified in more

details, budget is estimated:• Budgetary estimates: +25% -10%.

– When project resources and activities are highly detailed:• Definite estimates: +10% -5%.

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Time Management(Major Phases)

• Activity Definition:– Identifying specific activities that must be

performed to produce project deliverables.• Activity Sequencing:

– Identifying and documenting interactivity dependencies.

• Activity Duration Estimation:– Estimating the number of work periods required to

complete individual activities.• Schedule Development:

– Analyzing activity sequences, activity durations, and resource requirements to create a schedule.

• Schedule Control:– Controlling changes to project schedule.

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Time Management


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Activity Definition(Introduction)

• Involves identifying and documenting specific activities that must be performed to produce deliverables and sub-deliverables in work breakdown structures.

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• Work breakdown structures:– Deliverable-Oriented:

• Deliverables are listed in WBS.– Task-Oriented:

• Tasks to produce deliverables are listed in WBS.

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• If WBS is deliverable-oriented,– Activity definition generates activities for

creating deliverables defined in WBS.– So output is called the activity list.

• If WBS is task-oriented,– Activity definition is performed in

coordination with scope definition to determine both deliverables and tasks in WBS.

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Activity Definition(Inputs)

• Work breakdown structure• Scope statement• Historical information• Constraints• Assumptions• Expert judgement

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• Work breakdown structure:– A deliverable-oriented WBS

• Scope statement:– Contains project objectives.

• Historical information:– Historical information collected in

previous projects could be helpful for doing estimations.

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• Constraints:– Factors limiting development options.

• Assumptions:– Factors that are accepted as true.

• Expert judgement:– Experts could be very useful in clarifying

inputs.

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Activity Definition (Tools & Techniques)

• Templates • Decomposition

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• Templates:– An activity list from a previous project can

be used as a template for the new project.

– These templates, may also include;• Resource skills and • Required hours of effort for common

activities.

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• Decomposition:– Involves sub-dividing project work

packages into smaller components.– Final outputs should be described as

activities, not as deliverables.

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• Decomposition:– Decompose an activity until the activity;

• Can be performed by one person or a well-defined group;

• Has a single, clearly identifiable deliverable;

• Has a known method or technique;• Has well-defined predecessor and

successor steps;• Is measurable so that level of

completion can be determined.

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• Decomposition:– Rolling wave planning:

• Often, activities for the next few steps can be planned at a sufficient level of detail.

• In this case, rolling wave planning technique is used.

• Closest activities are planned at a detailed level;

• Activities farther in the future are planned only at a general level.

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Activity Definition (Outputs)

• Activity list• Supporting detail• Work breakdown structure updates

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• Activity list:– Includes all activities that will be

performed within the project.– Should be an extention to WBS if a

delivery-oriented WBS is used.– Should be clear enough to let team

members understand the content.

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• Supporting detail:– Includes all identified constraint and

assumptions, and other related details.• Work breakdown structure updates:

– Any missing deliverable identified during the activity definition should be integrated to WBS.

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Time Management


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Activity Sequencing(Introduction)

• Involves identifying and documenting interactivity logical relationships.

• Activities must be sequenced accurately to support later development of realistic and achievable schedule.

• In this phase, a network diagram will be generated to identify sequence.

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Activity Sequencing(Inputs)

• Activity list• Product description• Mandatory dependencies• Discretionary dependencies• External dependencies• Milestones

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• Activity list:– List of activities for producing

deliverables.• Product description:

– Product characteristics may affect sequencing,

– So they should be reviewed to ensure accuracy.

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• Mandatory dependencies:– Those that are inherent in the nature of

work being done.– For instance, implementation should be

started before testing.– Also called hard logic.

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• Discretionary dependencies:– Those that are defined by the project

management team.– Should be used with care,

• Since they may limit later scheduling options.

– Also called;• Soft logic, • Preferred logic or • Preferential logic.

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• External dependencies:– Those that involve a relationship between

project activities and nonproject activities.

– For instance, programming language software should be delivered before implementation starts.

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• Milestones:– Deadlines that are forced by the

stakeholders’ requirements.– Milestone events need to be part of

activity sequencing to assure that requirements for meeting milestones are met.

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Activity Sequencing (Tools & Techniques)

• Precedence diagramming method (PDM)• Arrow diagramming method (ADM)• Conditional diagramming method• Network templates

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• Precedence diagramming method (PDM):– A method of constructing a project

network diagram;• That uses boxes or rectangles (nodes)

to represent activities, and • Connects them with arrows that show

dependencies.

A D

B E

F

End

C

Start

G

Dummy node Dummy node

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• Precedence diagramming method (PDM):– Has the ability to illustrate four types of

task dependencies among activities.– Types of dependencies:

• Finish-to-start• Start-to-start• Finish-to-finish• Start-to-finish

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• Precedence diagramming method (PDM):– Finish-to-start:

• One activity cannot start until another activity has been completed.

• For instance, programmers cannot start programming until programming language has been chosen.

• The most commonly used logical relationship type.

P.L. chosen Programming

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• Precedence diagramming method (PDM):– Start-to-start:

• The start of sucessor depends on the start of predecessor.

• For instance, programming cannot start until some portion of program design is decided on.

Designing

Programming

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• Precedence diagramming method (PDM):– Finish-to-finish:

• Completion of successor activity depends on the completion of the predecessor.

• For instance, testing a system cannot be finished until programming is completed.

Programming

Testing

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• Precedence diagramming method (PDM):– Start-to-finish:

• Completion of the successor activity depends on the beginning of the predecessor.

• For instance, backuping first version of code segment cannot be completed until programming begins.

• Rarely used.

Programming

Backuping code

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• Arrow diagramming method (ADM):– Another network diagramming technique

that represents project activities as arrows and connects them at nodes to show their dependencies.

1

2

3

4

6

5

7

A = 2

B = 3

F = 2

C = 1

D = 1

E = 5

H = 5

I = 3

J = 4

G = 2

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• Arrow diagramming method (ADM):– Uses only finish-to-start dependencies.– May require use of dummy activities to

define all logical relationships correctly.

1

2

3

4

5

6

A

B

D

C

E

F

Dummy activity

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• Conditional diagramming method:– Used for defining nonsequential activities

such as conditional branches and loops.

Perform testing Implementation Completed?

Perform implementation

Start implementation

End implementation

Yes

No

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• Network templates:– Standardized networks can be used to

accelarate preparation of network diagrams.

– Portions of networks are offen reffered to as subnets or fragnets.

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Activity Sequencing (Outputs)

• Project network diagram• Activity list updates

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Activity Sequencing (Outputs)

• Project network diagram:– May include full project details or have

summary activities. – Any unusual sequence should be fully

described.• Activity list updates:

– Activity definition process may generate updates to activity lists.

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Time Management


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Activity Duration Estimation(Introduction)

• Process of taking information on project scope and resources, and

– Then developing durations for input to schedules.

• Inputs for estimates of a duration typically originate from person or group on project team who is most familiar with the nature of a specific activity.

• Estimates are often progressively elaborated.

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Activity Duration Estimation(Introduction)

• Estimating number of work periods required to complete an activity will often require consideration of elapsed time.

– Weekends and holidays should be considered.

– For instance, • If a task requires 3 days of work, but

first day begins on Friday, • Then elapsed time will be 5 days

because of weekend.

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Activity Duration Estimation (Inputs)

• Activity list• Constaints• Assumptions• Resource requirements• Resource capabilities• Historical information• Identified risks

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• Activity list:– List of activities for producing

deliverables.• Constaints:

– Factors limiting the development options.• Assumptions:

– Factors that are accepted as true.

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• Resource requirements:– Duration of most activities will be

significantly influenced by the resources assigned to them.

– For instance;• Allocating two people to a task may

halve the time required to complete the task.

• Allocating a half-time person to a task may double the time required to complete task.

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• Resource requirements:– Increasing number of personnel assigned

to a task does not necessarily mean reducing the time linearly.

– Because additional resources will increase communication overload.

– Also some tasks may not be performed in parallel.

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• Resource capabilities:– Duration of most activities will be

significantly affected by the capabilities of human and material resources assigned to them.

– For instance, assigning an experienced person to a task will reduce the time required to complete the task.

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• Historical information:– Likely durations of activities can be

estimated from historical information.– Possible sources:

• Project files• Commercial duration estimation

databases• Project team knowledge

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• Historical information:– Possible sources:

• Project files: – Records of previous projects that

the organizations in the current project were involved in.

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• Commercial duration estimation databases:

– Some historical information that could be available commercially (e.g. How long a governmental agency usually takes to respond to certain types of requests).

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• Project team knowledge: – Individual members of team may

» Remember previous actuals or estimates, and

» Use their experience.– These estimations are generally

less reliable than documented results.

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• Identified risks:– Project team should consider identified

risks when producing duration estimates.– Since risks can have significant influence

on durations.– Revise baseline duration estimations for

activities having risks with high probability of impact.

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Activity Duration Estimation(Tools & Techniques)

• Expert judgement• Analogous estimating• Quantitatively based durations• Reserve time (contingency)

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• Expert judgement:– Durations are often difficult to estimate

Because of number of factors that can influence them.

– Expert judgement should be used if possible, else it would be risky.

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• Analogous estimating:– Means using actual duration of a

previous, similar activity as the basis for estimating duration of a future activity.

– Also called top-down estimating.– A form of expert judgement.

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• Quantitatively based durations:– Quantities to be performed for each work

category, when multiplied by productivity unit rate, can be used to estimate activity durations ( Quantity x Productivity )

– Quantities: e.g. number of drawings, number of functions.

– Productivity unit rate: e.g. hours per drawing, hours per function.

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• Reserve time (contingency):– To reduce risks,

• Project team may add some extra time frame to risky activity durations or elsewhere in schedule.

– This extra time is called;• Time reserve,• Contingency or• Buffer.

– Can be either in percentage or a fixed amount.

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Activity Duration Estimation(Outputs)

• Activity duration estimates• Basis of estimates• Activity list updates

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• Activity duration estimates:– Should always include some indication of

range of possible results.– For instance,

• With high probability, activity will take 2 weeks ±2 days.

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• Basis of estimates:– Assumptions made in developing

estimates must be documented.• Activity list updates:

– Process may generate updates to activity lists.

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Time Management


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Schedule Development(Introduction)

• Means determining start and finish dates for project activities.

• Schedule development process must often be iterated a number of times prior to determination of final project schedule.

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Schedule Development(Inputs)

• Project network diagram• Activity duration estimations• Resource requirements• Resource pool description• Calenders• Constraints• Assumptions• Leads and lags• Risk management plan• Activity attributes

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• Project network diagram:– Shows activity sequencing.

• Activity duration estimations:– Shows number of work periods required

for each activity.• Resource requirements:

– Include number of resources assigned to tasks.

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• Resource pool description:– Stores knowledge of what resources will

be available at what times and in what patterns.

– For instance, a shared or critical resources can be difficult to schedule

• Since their availability may be highly variable.

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• Resource pool description:– Amount of detail may vary in time.– For instance,

• For preliminary schedule,– One may only need to know

number of consultants required.• For final schedule,

– One may need to know which specific consultants are required.

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• Calenders:– Project and resource calenders identify

periods when work is allowed. – Project calenders affect all resources

(e.g. 5 day work in a week).– Resource calenders affect a specific

resource or a category of resources (e.g. A staff may be on vacation, a half-time staff).

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• Constraints:– Factors that will limit the development

options.– Major time constraints:

• Imposed dates• Key events or milestones

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• Constraints:– Major time constraints:

• Imposed dates:– Restrics activities as to;

» Start no earlier than a specific date or

» Finish no later than a specific date.

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• Constraints:– Major time constraints:

• Key events or milestones:– Completion of certain deliverables by a

specific date may be requested » By customer, sponsor or Other

stakeholders.– Once scheduled,

» These days become expected, and» Often may be moved with great

difficulty.

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• Assumptions:– Factors that are accepted as true.

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• Lead time:– Time required by one task before another

task can begin.– For instance, in start-to-start relation,

• Testing can only be started after some portion of code is implemented.

Implementation

Testing

Lead time

Development

Quality Inspection

Lead time

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• Lag time:– Time delay between completion of one

task and start of its successor.– For instance, in finish-to-start relation,

• Testing can only be started after implemention and compiling code are completed.

Implementation Testing

Lag time (Compiling)

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• Risk management plan:– A plan for detecting, monitoring risks and

minimizing their impacts.• Activity attributes:

– Attributes of activities including;• Responsibility (who),• Geographic area or building (where),• WBS classification (which branch),• Activity type (other details),

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Schedule Development (Tools & Techniques)

• Matematical analysis• Duration compression• Simulation• Resource leveling• Project management software• Coding structure

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• Matematical analysis:– Involves calculating;

• Theoretical early and late start and finish dates for all project activities

– Without regard for any resource pool limitations.

– Result is not a schedule, • But indicate time periods within which

activity could be scheduled – Given resource limits and other

known constraints.

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• Matematical analysis:– Most widely known techniques:

• Critical path method (CPM)• Graphical evaluation and review

technique (GERT)• Program Evaluation and Review

Technique (PERT)

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• Matematical analysis:– Critical path method (CPM):

• Calculates a single, deterministic early and late start and finish date for each activity;

• Based on deterministic network logic and duration estimates.

1

2

3 65

6

4

7

Early start

D = 1

Late start Early finish

Late finish

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• Matematical analysis:– Graphical evaluation and review

technique (GERT):• A network analysis technique that

allows probabilistic network logic and duration estimates.

• Nowadays, not considered as a generally accepted and used scheduling technique.

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• Matematical analysis:– Program Evaluation and Review

Technique (PERT):• Uses a weighted average duration

estimate to calculate activity durations.

• Nowadays, seldomly used.

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• Matematical analysis:– Program Evaluation and Review Technique

(PERT):• Optimistic, most likely and pessimistic

durations are used.

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• Duration compression:– A special case of mathematical analysis;

• That looks for ways to shorten project schedule.

– Techniques:• Crashing• Fast tracking

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• Duration compression:– Crashing:

• Dedicating extra resources to an activity in an attempt to finish activity sooner than its normal schedule.

• For example, hiring an extra personnel for an activity.

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• Duration compression:– Fast tracking:

• Means performing activities in parallel that would normally be done in sequence.

• For instance, – Starting to write code before design

is completed.• Often results in rework and usually

increases risks.

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• Simulation:– A process of calculating different

scenarios and their effects on the project schedule.

– Scenarios, Project and activity durations, are generated using different assumptions, constraints and resource allocations.

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• Simulation:– Common used types are:

• Monte Carlo simulations• What-if analysis.

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• Simulation:– Monte Carlo simulations:

• Probabilistic analysis used to calculate a distribution of likely results.

• In our case, we analyze likely task and project durations.

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• Simulation:– What-if analysis:

• A process of evaluating alternative scenarios

– By observing how changes to selected factors affect other factors and outcomes.

• For instance, asks “what if a major component for a system is delayed”.

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• Simulation:– What-if analysis:

• Tries to assess the feasibility of schedule under unsuitable conditions.

• Helps preparing contingency/response plans for risks.

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• Resource leveling:– Any form of network analysis where

resource management issues drive scheduling decisions.

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• Resource leveling:– Matematical analysis produce early-start

schedules,• But these schedules may not be

feasible during some periods of time because of high resource requirements that exceeded available amount within the project.

– Resource leveling techniques reschedule activites in order to reduce resource requirements.

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• Resource leveling:– For instance,

• If we have one person and two tasks that were scheduled at the same time,

• Resource leveling may push one of the tasks further in the future.

Implementing A

Implementing B

Implementing A

Implementing B

Initial schedule Resource leveled schedule

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• Resource leveling:– Allocate scare resource to critical path

activities first approach can be applied;• To develop a schedule that reflects

such contraints.– Often results in a project duration longer

than the preliminary schedule.

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• Project management software:– Widely used to assist with schedule

development.– These products automate calculation of

matematical analysis and resource leveling,

– Therefore allow rapid consideration of schedule alternatives.

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• Coding structure:– Use coding structures to help identifying,

sorting, categorizing activities.– For instance,

• Code:– Project phase,– Activity responsibility,– Schedule level, etc.

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Schedule Development (Outputs)

• Project schedule• Supporting detail• Schedule management plan• Resource requirement updates

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• Project schedule:– Includes at least planned start and

expected finish dates for each activity.– Remains preliminary until resource

assignments are confirmed.

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• Supporting detail:– Includes at least documentation of all

identified constraints and assumptions.– For instance;

• Resource histograms

• Alternative schedules• Schedule contingency reserves

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• Schedule management plan:– Defines how changes to schedule will be

managed.• Resource requirement updates:

– Resource leveling may have significant effects on resource requiements.

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Time Management


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Schedule Control(Introduction)

• Influencing factors that create schedule changes to ensure that changes are agreed upon.

• Determining that schedule has changed.• Managining actual changes when and as

they occur.• Should be integrated with other control

processes (e.g. integration change control, scope change control...).

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Schedule Control(Inputs)

• Project schedule• Performance reports• Change requests• Schedule management plan

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• Project schedule:– The approved project schedule is called

the schedule baseline.– Basis for measuring and reporting project

performance.• Performance reports:

– Provide information on schedule performance.

– For instance, which dates have been met and which have not.

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• Change requests:– May occur in many forms – May require extending schedule or – May allow accelerating it.

• Schedule management plan:– Defines how changes to schedule will be

managed.

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Schedule Control(Tools & Techniques)

• Schedule change control system• Performance measurement• Additional planning• Project management software• Variance analysis

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• Schedule change control system:– A system that defines procedures by

which project schedule may be changed.– Includes tracking systems, paperwork...

• Performance measurement:– Any technique to asses magnitude of

variations that occur.– Helps to decide if schedule variations

requires corrective actions.

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• Additional planning:– If any changes are required on schedule,

• Includes revising activity durations, activity sequences, and alternative schedules.

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• Project management software:– Very useful for;

• Tracking planned dates versus actual dates,

• Forecasting effects of schedule changes.

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• Variance analysis:– During schedule monitoring, regularly

performing variance analysis is important.

– Includes comparison of planned and actual or forcast start and finish dates

• In order to see affects of variations.– Particular attention should be given to

critical and sub-critical activities.

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Schedule Control(Outputs)

• Schedule updates• Corrective actions• Lessons learned

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• Schedule updates:– Any modification to schedule information.– Approved schedule updates are called

revisions.• Corrective actions:

– Anything done to bring expected future performance in line with baseline schedule.

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• Lessons learned:– Causes of variances,– Reasoning behind corrective actions,– Other types of lessons learned should be

documented for the future use.

cs-413 1 time management (part 9) bilgisayar mühendisliği bölümü – bilkent Üniversitesi –...

Documents

project resources

project deliverables

project progress

timely completion of

activity durations

activity sequences

boehm slide

work tasks schedule